package mo.leetcode_hot;

import java.util.Stack;

public class L20 {

    public boolean isValid(String s) {
        Stack<Character> stack = new Stack<>();
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            if (c == '{' || c == '(' || c == '[') {
                stack.push(c);
            } else {
                if (stack.isEmpty()) {
                    return false;
                }
                char pop = stack.pop();
                if ((pop == '{' && c != '}') || (pop == '[' && c != ']') || (pop == '(' && c != ')')) {
                    return false;
                }
            }
        }
        return stack.isEmpty();
    }

}
